Mapping QTL conferring speckled snow mold resistance in winter wheat (Triticum aestivum L.)

Speckled snow mold caused by Typhula ishikariensis is one of the most devastating diseases of winter wheat in Hokkaido, Japan and parts of the Pacific Northwest region of USA. Münstertaler is a winter wheat landrace from Switzerland that has very high resistance to snow mold and superior freezing tolerance. Quantitative trait loci (QTL) for resistance to speckled snow mold were identified in a doubled haploid population derived from a cross between Münstertaler and susceptible variety Ibis, both under field conditions and controlled environment tests. Composite interval mapping analysis revealed a major QTL on chromosome 5D from Münstertaler, and on chromosome 6B from Ibis. Flanking microsatellite marker cfd 29 for the QTL on chromosome 5D was about 5 cM distant from vernalization requirement gene Vrn-D1, suggesting that the QTL on chromosome 5D is located on a cold-stress-related gene cluster along with Vrn-D1 and freezing tolerance gene Fr-D1. The QTL on chromosome 6B from Ibis was located on the centromere region flanking QTn.mst-6B, which is reported to increase plant tiller number.